I am getting an edelbrock AF monitor and I want to know what a safe reading is. I know that 14.7 is right on or something like that but what is the lowest lean ratio to worry about. The monitor goes from 12 to 15. Which one is rich and which one is lean? thanks for the help

 

i would keep it in thje 13-1 range. like 13.5 or somthing, 14 is good to but better safe then sorry right?

if youre engine is a bit on the rich site it wont cost you any hp (1 % max) but a bit on the lean site will kill hp big time!

Plus, it will make your engine overheat and **** like that.

Just watch the lights on the af monitor, green is good.

i use a o2 sensor and a voltage meter.

 

14.7 is stoich for maximum efficiency (air temps optimized and fuel efficiency is at its best). Peak power has its potential around 12.5, but is harder on parts. 13 sounds good.

As for what is what, think about it. It's the air to fuel ratio. Take 14.7:1 for example. 14.7:1 being air, 1 being fuel. Increase or decrease the first (larger) number. larger the number, more air, same amoung of fuel = lean. smaller first number, less air per fuel = richer.

 

Hey thanks guys

 

AF ratio gages for our cars are eye candy only. The stock 02's are horribly inaccurate when stochiometric condictions stray beyond +/- 1 or 2%. A wide band 02 is the only tool you should really use to correctly base your AF ratio. Running slightly rich and lean can have performance, wear and tear as well as emissions effects. Most eninges out there are desinged either slightly rich or slightly lean. There are benifits and hinderances of both.

 

Well, you know we always wondered about them A/F Monitors. I had a K&N A/F M in my car for years and used it to dial in my jetting (Q-Jet). A friend of mine has built engines for years and finnished second in the first PHR Engine Masters contest. I swore by them so he bought two and took them to the dyno where he was going to run in a customers engine. They installed the O2 senors ( stock chevy) in the headers collectors and taped the monitor to the glass. Man they were dead nuts with the air/fuel ratios printed out on the dyno sheets.

Auggie

 

Sinlge wire 02's are no where near as accurate as 3 and 4 wire heated ones. So I geuss it depends on what ones you use. You may be able to play around with them ar part throttle, but the ECM does not use 02 output when at WOT. That is where the wide band comes into.

 

Well, all the sinlge wire O2 sensors that I have installed for A/F Monitors are not using the ECM O2 sensor. I weld a bung (as in my case 84 Z28) just behind the "Y" pipe so it sees all eight cyls.

Auggie

 

Doesn't make much difference, the single wire sensors for the aftermarket gauges with the pretty lights are the same type of cheap narrowband sensor as the ECM uses.

 

think of the stock sensor as a switch, its either rich or lean, you have no way of knowing how much in either direction.

 

Well, you do, but it's extremely sensitive around stoich, and gets pretty insensitive in a hurry the richer or leaner you get.

 

since were talking here...




thats a pretty steep slope

 

Well, all I can tell you is that those little red lites react instantly to the touch of the pedel. I can understand that if you have never used one that you might feel that way but the dyno testing that we did confirmed the accuracy of them there A/F Monitors. In fact the eng. builder that said he would never have one in his car ( Corvette) has two of them now. One for each bank. He had a power valve (Holly) failure and man all the lights lit up like a X-mas tree.

Auggie

 

Of course they react instantly. Look at the graph that nsimmons posted, and mentally divide the vertical scale into 8 bars, each representing an LED on a gauge. Now look at what happens if the mixture changes from say 14.8 to 14.6. Not much of a change in mixture, but you've probably moved 3 or 4 LEDs. Now imagine going from 15:1 to a dangerously lean 18:1. Big change in mixture, but I doubt if you'd even change 1 bulb. The same goes for a change from 14:1 to a piggishly rich 12:1 or 11:1.

 

Well, heres the diff between lites.

Lite #1 = 16.9
2 = 16.1
3 = 15.4
4 = 14.7
5 = 14.0
6 = 13.3 (my WOT)
7 = 12.5
8 = 11.8
9 = 11.0
10 = 10.3

Works for me


Auggie

 

anyone know what the vertical lit A/F guages "bar count" would be equivalent in actual A/F ratios like Auggie just posted?

Actually i just checked and the one i mean is like the Nordskog # M7009 or the Summit brand #G2986

and Auggie, who/what /where did you get these numbers?

 

Auggie, i have something similar to the Nordskog (NRD-M7009) and the Summit (SUM-G2986) A/F guages. I see that these are also on a 10 bar scale.

Where did you get these numbers? Is it a 100% confirmation? and also....are these #'s correct for thes style A/F guages?

 

its wrong wrong wrong..ive done enough ecm tweaking to know they are useless for power tuning. get a wide band. disagree with me? hit the prom forum and state your claim.

 

Chevyboy07 91, I bought my first A/F Monitor from K&N in 1988 and the A/F ratio numbers came with the instruction sheet. I also have a Cyberdyne ( #7009) Vertical Bar Graph A/F Moitor on my 1999 Dodge Durango and here are the numbers that came with that instruction sheet.

#1 = 17.1 to1
#2 = 16.5
#3 = 16.1
#4 = 15.4
#5 = 14.9
#6 = 14.4
#7 = 13.8
#8 = 13.2
#9 = 12.7
#10 = 12.1

All these numbers are for gasoline.

Auggie

 

well I got it installed and working. Heres what it has shown me. When at a steady speed I am running around the 12-12.5 lights but when I get on it heavily it pretty much goes to the red light which is 15 or so. Even if I am at a very heavy accel it still will flatten back out to 12.5 range. So would the lean condition be caused my the accel pumps?

 

Well, that is confusing. You said that you have a vertical monitor right. Here is how mine reads.

TOP OF GAUGE

Red = 17.1
Red = 16.5
Orange = 16.0
Orange = 15.4
Yellow = 14.9
Yellow = 14.4
Orange = 13.8
Orange = 13.2
Red = 12.7
Red = 12.1

At cruising speeds (60 to 80mph) I read 15.4 to 16.0. At WOT it starts out at 12.1 and ends up at 13.2 (145mph). Hope this helps.

Auggie

 

no I have a edelbrock horizontal monitor. Mine only has 7 lights in all. 2 yellow, 4 green, and 1 red.

 

Well, on my horizontal gauge left is lean and right is rich. I guess you will just have to give them a call and see what they say. Let us know what they say.

Auggie

 

yeah mine goes left is rich and the further left it goes it gets leaner.

here are the lights from left to right,

#1---12---yellow
#2---12.5--yellow
#3---13---green
#4---13.5---green
#5---14---green
#6---14.5---green
#7---15---red